Preparation Of New Materials For Solid Phase Extraction And Its Application To Analysis Of Trace Heavy Metal Ions

Heavy metal pollution has attracted nationwide attention. Cadmium, copper and nickel are typical heavy metal elements, while the hazardous effects of silver on human health and the environment is now being increasingly revealed. Atomic absorption spectrometry is a common method for determination of heavy metals, especially flame atomic absorption spectrometry (FAAS) is the most widely used technique due to its easy operation, rapidity and low cost. However, in many cases, it is very difficult to carry out direct determination by using FAAS, because of the low content of heavy metal ions and complicated matrix composition in environmental samples. Thus, sample pretreatment prior to instrumental analysis is often essential. Nowadays solid-phase extraction (SPE) has become the most commonly used method for sample preparation, because of its high recovery and enrichment factor, environment-friendly, and simple operation. The key factor of solid phase extraction technology is the sorbent, and the widely used C18-bonded silica lacks of selectivity. Furthermore, column SPE usually takes a long time. Therefore, the development of efficient, selective and rapid SPE techniques based on new adsorbent for trace analysis of heavy metals is of important significance.The main contents include the following four parts:1.Introduces the research background and significance of the work,an overview of cadmium,copper,nickel and silver commonly used detection methods,profile of the solid-phase extraction technology,nano-materials and atomic absorption spectrometry,as well as in environmental analysis application.2.With fine glass beads as the carrier,using the sol-gel method load titanium dioxide,followed modified by ionic liquid1-octyl-3-methylimidazolium hexafluorophosphate,has been modified with an ionic liquid surface supported nanomaterials.Scanning electron microscopy,fourier transform infrared spectroscopy were used to characterize the material and conducted TGA.The results show titanium dioxide having nanoscale particle,on its surface has been successfully modified with ionic liquid.Adsorption isotherm test results show that,Cd2+andCu2+adsorption on the material compliance Langmuir equation.Use this material as a solid phase extraction column filler,not only to improve the surface properties of titanium dioxide,but also to avoid common nanomaterials small size,easy to plug through the column when the phenomenon.3.Ionic liquid-modified glass beads load nano titanium dioxide material enrichment Flame atomic absorption spectrometric method for the determination of trace cadmium and copper.The factors that affect the recoveries of cadmium and copper ions.Including water sample pH, amount of adsorbent, the amount of the chelating agent,the injection flow rate,eluent.Also studied coexisting ions and repeated recycling.Under optimum conditions, determination the detection limit and stability of cadmium and copper ions.Detection of cadmium and copper in urban rivers water and lakes water, with satisfactory results.the detection capability of method is strong.The advantages include easy operation,higher enrichment efficiency,low-cost analysis,with good application value.4.Preparation a new magnetic nano-materials modified with octadecyl trimethoxysilane.tri-iron tetroxide as magnetic collective Preparation by sol-gel method,magnetic nano-materials coated with a core-shell structure after coated silica.Then modified octadecyl trimethoxysilane by way of the water bath was stirred.Scanning electron microscopy,fourier transform infrared spectroscopy were used to characterize the material and conducted TGA and magnetic analysis.Characterization display material having a particle size of the nanoscale, the successful modification of the octadecyl trimethoxysilane, a saturation magnetization of16.40emu/g.Prepared functional materials for the three metals Cd2+,Ni2+and Ag+adsorption kinetics conform HO quasi-two dynamic equations and thermodynamics conform the Langmuir adsorption isotherm.The three ions are AH<O,indicating that they are exothermic adsorption process.5.Establish octadecyl trimethoxysilane modified the magnetic nanomaterials enrichment-flame atomic absorption spectrometric method for the determination of trace cadmium,nickel and silver.The factors that affect the recoveries of cadmium,nickel and silver ions.Including water sample pH,amount of adsorbent,the amount of the chelating agent,the adsorption time,eluent,coexisting ions.Under the optimum conditions,the method Cd2+,Ni2+and Ag+detection limits were0.05,0.10and0.15μg/L,the relative standard deviation (RSD) between1.4%-2%. River water and lake water samples were measured,and the recoveries of Cd2+,Ni2+and Ag+were83.53%-97.67%,90.23%-102.27%,85.00%-93.67%.